import math

x1,y1,x2,y2=map(float,input().split())
x=x2-x1
y=y2-y1
a=x*x+y*y
print("{:10f}".format(math.sqrt(a))) import math math x1,y1,x2,y2=map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 x=x2-x1 x x2-x1 x2 x1 y=y2-y1 y y2-y1 y2 y1 a=x*x+y*y a x*x+y*y x*x x x y*y y y print("{:10f}".format(math.sqrt(a))) print "{:10f}".format(math.sqrt(a)) "{:10f}".format "{:10f}" format math.sqrt(a) math.sqrt math sqrt a y1,x2,y2=map(float,input().split()) map(float,input().split()) y1 x=x2-x1 x2-x1 x x2,y2=map(float,input().split()) map(float,input().split()) x2 a=x*x+y*y x*x+y*y a y2=map(float,input().split()) map(float,input().split()) y2 y=y2-y1 y2-y1 y x1,y1,x2,y2=map(float,input().split()) map(float,input().split()) x1
import math

x1,y1,x2,y2=map(float,input().split())
x=x2-x1
y=y2-y1
a=x*x+y*y
print("{:10f}".format(math.sqrt(a)))
